Portable fan



FIG. 1 is a perspective view of a portable fan, showing my new design;

FIG. 2 is a right side elevational view;

FIG. 3 is a top view;

FIG. 4 is a front elevational view;

FIG. 5 is a bottom view;

FIG. 6 is a left side elevational view; and,

FIG. 7 is a back view.

The broken line showing of environmental structure in FIGS. 1-7 is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a portable fan, as shown and described. 